A federal mediator is being brought in to meet with both sides: the United Food and Commercial Workers union and Southern California's biggest supermarket operators.

With little progress being made in contract talks between Southern California's major grocery chains and the union representing 62,000 of their workers, a federal mediator is being brought in to meet with both sides in the coming weeks.

Officials of the United Food and Commercial Workers, citing a news blackout over the negotiations, declined to say which side contacted the federal Mediation and Conciliation Service.

Representatives of Ralphs, Vons and Albertsons — the three big chains in the talks — could not be reached for comment late Friday.

Last week, the union said its members had voted overwhelmingly to authorize their leaders to call a strike if they couldn't reach an agreement on a new contract with the supermarket operators.

The strike authorization, which required the backing of at least two-thirds of those voting to pass, does not mean that a walkout or an employer lockout is imminent. Some analysts said the vote could help jump-start the talks, which have dragged on for weeks.

The negotiators are trying to replace a four-year contract that was set to expire March 6 but is being extended day to day. The contract covers supermarket checkers, baggers, meat cutters and other unionized employees of Ralphs, which is owned by Cincinnati-based Kroger Co.; Vons and Pavilions, owned by Safeway Inc. of Pleasanton, Calif.; and Albertsons, owned by SuperValu Inc. of Eden Prairie, Minn.